Sanding tool with molding interface pad

ABSTRACT

A hand-held, manually-operated, sanding tool for use with a replaceable sheet-like abrasive material, such as sandpaper, includes a base member, a molded interface pad provided on the base member to define a working face against which the sheet-like abrasive material is arranged, and a retaining mechanism arranged to maintain the sheet-like abrasive material in operative relation with the interface pad. The base member is formed of a first material and the molded interface pad is formed of a second injection moldable material

BACKGROUND

The present invention relates generally to hand-held, manually-operated,sanding tools that use a sheet of abrasive material such as sandpaper.

Manually-operated hand sanding tools, such as sanding blocks, arecommonly used with abrasive sheets, such as conventional sandpaper, tohand sand or finish a work surface. A commercially available sandingblock is the 3M™ Rubber Sanding Block available from 3M Company, St.Paul, Minn. Hand sanding tools may include a foam interface pad that isadhesively bonded to the working face of the sanding tool. Suchinterface pads, however, suffer from one or more drawbacks orshortcomings. It would be desirable to provide a hand-held,manually-operated, sanding tool that includes an interface pad thatovercomes the drawbacks and shortcomings of sanding tools havingadhesively bonded foam interface pads.

SUMMARY

The present invention provides a hand-held, manually-operated, sandingtool for use with a replaceable sheet-like abrasive material thatincludes a base member formed of a first material, a molded interfacepad formed of a second injection moldable material provided on the basemember, thereby defining a working face against which the sheet-likeabrasive material is arranged, and a retaining mechanism arranged tomaintain the sheet-like abrasive material in operative relation with theinterface pad.

In one aspect, the first material has a Shore hardness that is greaterthan the Shore hardness of the second material (i.e. the interface padis softer than the base member). In a more specific aspect, the firstmaterial has a Shore D hardness of greater than about 30, and the secondmaterial has a Shore A hardness of less than about 95.

In one embodiment, the interface pad is a polymeric material. In a morespecific embodiment, the interface pad is an elastomeric material. Inanother aspect, the interface pad includes a textured working surfaceopposite the base member. In more specific aspects, the interface padworking face includes a macroscopically three-dimensional surfacetopography. The surface topography may comprise a randomthree-dimensional surface topography or it may comprise a regularnon-random pattern defined by raised regions and recessed regions.

In another aspect, the base member contains slots and the interface padincludes extensions extending into the slots, thereby to form a secureconnection between the base member and the interface pad.

In yet another aspect, the present invention provides a method of makinga hand-held, manually-operated, sanding tool for use with a replaceablesheet-like abrasive material comprising a base member formed of a firstmaterial, a molded interface pad formed of a second injection moldablematerial provided on the base member, thereby defining a working faceagainst which the sheet-like abrasive material is arranged, and aretaining mechanism arranged to maintain the sheet-like abrasivematerial in operative relation with the interface pad, wherein themethod comprises the steps of providing a sanding tool including a basemember having a working face, and forming an interface pad on the basemember by injection molding an elastomeric material over the workingface.

Advantages of certain embodiments of the invention include improvedsanding capability, improved product design flexibility (that is, theproduct design can be more easily tailored or adapted to a specificend-use application), easier and less expensive manufacturing, and asanding tool that is easier and more comfortable to use.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be further described with reference to theaccompanying drawings, in which:

FIG. 1 is a perspective view of a hand-held, manually-operated, sandingtool having a molded interface pad according to the invention;

FIG. 2 is a side view of the sanding tool of FIG. 1;

FIG. 3 is a detailed view of the base member and the interface pad; and

FIGS. 4 a and 4 b are plan views showing alternate three-dimensionalsurface topographies for the interface pad.

DETAILED DESCRIPTION

Referring now to the drawings, wherein like reference numerals refer tolike or corresponding parts throughout the several views, FIGS. 1 and 2,show a hand-held, manually-operated sanding tool or sanding block 2 foruse with a flexible, replaceable, sheet-like abrasive material 40. Theterm “manually-operated” refers to the fact that the tool 2 is not apower tool. That is, all of the power for the tool is provided by theuser and the tool itself does not include a motor. The term “sheet-likeabrasive material” refers to thin, flexible, typically square orrectangular sheets of abrasive material having discrete ends that can beattached to a sanding block. Such sheet-like abrasive materials include,for example, conventional sandpaper, flexible sanding scrims, non-wovenabrasive materials such as Scotch-brite™ available from 3M Company, St.Paul, Minn., and thin flexible abrasive sheet materials such as thosedescribed in U.S. Pat. No. 6,613,113 (Minick et al.), the entirecontents of which are hereby incorporated by reference. The tool mayalso find use with non-abrasive sheet-like materials such as dustremoving tack cloth materials. The term, however, does not includeendless belts of abrasive material commonly used on power sanding tools,or die cut sheets that are sold pre-cut to match the size and shape of aparticular sanding tool as is commonly done for power detail sandingtools.

The sanding tool 2 shown and described herein is described more fully inU.S. patent application Ser. No. 11/117,932 filed Apr. 29, 2005, theentire contents of which are hereby incorporated by reference. For thepresent invention, however, the sanding tool 2 generally is notparticularly significant as long as it is capable of including aninterface pad and includes certain basic features such as the ability toreceive and retain a sheet-like abrasive material. Thus, it will beunderstood that the sanding tool 2 shown and described below is intendedto represent any sanding tool capable of having a molded interface pad.

The sanding tool 2 includes a base member 4 and a pair of clampingmechanisms 6, 8 connected with opposed ends of the base member 4.Although the sanding tool 2 is shown with clamping mechanisms 6, 8 atboth ends, it will be recognized that one or both of the clampingmechanisms 6, 8 may be replaced with a conventional mechanism forsecuring the abrasive sheet-like material 40 to the tool. It will alsobe recognized that although the base member 4 is shown as beingrectangular, it may also be square or other shapes that lend themselvesfor use with conventional abrasive sheets.

The base member 4 has first 10 and second 12 opposed ends and agenerally planar bottom surface 14. Each end 10, 12 of the base member 4has an inclined or angled contact surface 16, 18, respectively, oppositethe bottom surface 14. In this manner, the contact surfaces 16, 18 andbottom surface 14 form an acute angle relative to the associatedadjacent end 10, 12, respectively.

Each clamping mechanism 6, 8 is pivotally connected with opposite ends10, 12 of the base member 4 adjacent the contact surface 16, 18,respectively, thereby defining a jaw into which the ends 40 a, 40 b of asheet-like abrasive material 40 may be inserted. Each clamping mechanism6, 8 is movable between a closed position shown in FIG. 1, and an openposition shown in FIG. 2. In the closed position, the clampingmechanisms 6, 8 are fully actuated toward the associated contactsurfaces 16, 18, respectively, and, when no abrasive material ispresent, are arranged adjacent to the contact surfaces 16, 18,respectively. In the open position, the clamping mechanisms 6, 8 arespaced from the associated contact surfaces 16, 18, thereby defininggaps 20, 21, respectively, between the base member 4 contact surfaces16, 18 and the clamping mechanisms 6, 8.

Each clamping mechanism 6, 8 includes a flexible tensioning member 22,24 arranged to face the associated contact surface 16, 18. Arranged inthis manner, as the clamping mechanisms 6, 8 are lowered toward the basemember 4 to secure the abrasive material 40 to the tool 2, the terminaledges of the tensioning members 22, 24 slidably engage the contactsurfaces 16, 18. Thus, when an end 40 a, 40 b of the abrasive sheet 40is inserted in the gap 20, 21 between the base member 4 and a clampingmechanism 6, 8, and the clamping mechanism is moved from its openposition to the closed position, the edge of the tensioning members 22,24 will frictionally engage the end 40 a, 40 b of the sheet of abrasivematerial 40.

As the clamping mechanisms 6, 8 are further urged toward the contactsurfaces 16, 18, the tensioning members 22, 24 grip the respective endsof the abrasive sheet 40 a, 40 b and move it upwardly along the inclinedcontact surfaces 16, 18 away from the associated end 10, 12, therebydrawing the sheet of abrasive material further into the gap 20, 21. Inaddition, as the clamping mechanisms 6, 8 are urged against the contactsurfaces 16, 18, the tensioning members 22, 24 bow or flex such that thebowed surface of the tensioning members 22, 24 will engage the contactsurfaces 16, 18, thereby increasing the overall contact surface areabetween the tensioning members 22, 24 and the sheet of abrasive material40. In this manner, slack in the abrasive sheet 40 is taken up, therebytightening the fit of the abrasive sheet 40 against the bottom 14 of thebase member 4.

In the illustrated embodiment, the tensioning members 22, 24 are thinflexible strips of metal, such as a leaf spring, that generally returnto their original positions when the applied force is released. Othermaterials such as a stiff resilient rubber or synthetic plastic materialmay also be used. To distribute the force applied by the tensioningmembers 22, 24 to the ends abrasive sheet 40 a, 40 b evenly (both duringthe installation of the abrasive sheet 40 onto the tool and while theabrasive sheet is being held onto the tool), the tensioning members 22,24 extend continuously across the entire width of the clampingmechanisms 6, 8. By distributing the force in this manner, thetensioning members 22, 24 have a reduced tendency to tear or otherwisedamage the abrasive sheet material 40.

To further reduce the likelihood that the ends of the tensioning members22, 24 will dig into the abrasive sheet 40, and thereby possibly damagethe abrasive sheet, in an alternative embodiment, the tensioning members22, 24 may be curved or bowed inwardly such that the tensioning members22, 24 have curved surfaces that face the contact surfaces 16, 18, andengage the contact surfaces when the clamping mechanisms 22, 24 areclosed.

In accordance with a characterizing aspect of the sanding tool 2, amolded interface pad 26 is provided on the bottom surface of the basemember 4. The interface pad 26 defines the surface against which thesheet-like abrasive material 40 is secured. By providing a moldedinterface pad 26, the base member 4 and interface pad 26 form anintegrally molded body including an upper portion defined by the basemember 4, and a lower portion defined by the interface pad 26. The basemember 4 is typically formed of a first polymeric material, and theinterface pad 26 is typically formed of a second polymeric material. Thesecond polymeric material used to form the interface pad 26 is typicallysofter than the material used to form the base member 4. The moldedinterface pad 26 may be formed of any moldable material but is typicallya soft, resiliently-flexible, elastomeric, injection moldable material.Suitable injection moldable materials include natural and syntheticrubbers including latex and butyl rubber, thermoplastic elastomers suchas polyurethane elastomers, thermoplastic vulcanizate, and thermoplasticrubber. Suitable materials for the interface pad 26 typically have aShore A hardness of less than about 95 and, more typically, less thanabout 70. A suitable material for the molded interface pad 26 isavailable from Advanced Elastomer Systems, an affiliate of ExxonMobilChemical, under the trade designation Santoprene.

Generally, the base member 4 is formed of a material having a Shorehardness that is greater than the Shore hardness of the material used toform the interface pad. Suitable materials for the base member includehard synthetic plastic materials, typically thermo set or thermoplasticmaterials such as ABS (acrylonitrile butadiene styrene), polypropylene,polyethylene, and blends containing such materials. Suitable materialsfor the base member 4 typically have a Shore D hardness of greater thanabout 30. A suitable material for the base member 4 is available from GEPlastics under the trade designation Cycolac and Cycoloy (an ABSpolycarbonate blend).

FIG. 3 is a detailed view showing the interconnection between the basemember 4 and interface pad 26. In the illustrated embodiment, the basemember 4 contains recesses or slots 28 and the interface pad 26 includesextensions 30 that extend into the slots 28. In this manner, amechanical connection, which resists dissociation, is formed between thebase member 4 and the interface pad 26. To further enhance theinterconnection between the interface pad 26 and the base member 4, andthereby prevent the interface pad 26 from separating from the basemember 4, the slots 28 include optional flared end regions 28 a, and theextensions 30 include flared terminal portions 30 a that extend into theflared end regions 28 a of the slots 28. Other structural features forforming the mechanical attachment between the base member 4 and theinterface pad 26 are contemplated in connection with the presentinvention. The mechanical connection may be formed, for example, by asingle protrusion, which may have a variety of shapes, that mates with acooperating recess. The protrusion and recess may be formed in eitherthe base member 4 or the interface pad 26.

Alternatively, base member 4 and the interface pad 26 may be formed viaa chemical bond. When attached by a chemical bond, the interface betweenthe base member 4 and the interface pad 26 may be generally planar (i.e.the base member 4 and the interface pad 26 each include generally planarsurfaces that are attached to each other) or the interface may includestructural features such as those described above to further enhance theinterconnection between the base member and the interface pad 26. Thechemical bond is formed by selecting compatible materials that form astrong chemical bond.

As shown in FIG. 4, the exposed working face of the interface pad 26(i.e. the surface of the interface pad 26 opposite the base member 4against which the abrasive sheet 40 is arranged) may include a texturedsurface 32 having a three-dimensional surface topography. Thethree-dimensional surface topography is typically macroscopic meaningthe height differential between the raised regions and the recessedregions is greater than about 1 millimeter. As shown in FIG. 4 a, thetextured surface 32 may be a random pattern of raised regions 34separated by recessed regions 36 or, as shown in FIG. 4 b, the texturedsurface may be a regular repeating pattern of raised regions 34 andrecessed regions 36. Other surface geometries are contemplated inconnection the present invention. For example, the size and shape of theraised and recessed regions may be varied or tailored depending on thetype of abrasive sheet used and/or depending on the specific end useapplication for the tool.

The combination of the base member 4 and the interface pad 26 may beformed, for example, using known multi-material injection moldingtechniques including co-injection molding, overmolding, and multi-shotmolding. For example, the base member 4 may be formed by injectionmolding a suitable material, such as ABS, into a mold to form the basemember 4, and the interface pad 26 may be formed by injection molding asuitable material, such as Santoprene, to form the interface pad 26.Alternatively, the base member 4 may be formed by casting or other knowntechniques.

Injection molding the interface pad 26 offers a number of advantagesover the use of conventional interface pads, which are foam pads thatare adhesively bonded to the sanding tool 2. First, because the moldedinterface pad is injection molded, the additional steps of die cutting afoam sheet to the appropriate size and adhesively bonding the foam padto the bottom of the base member 4 are eliminated. This simplifies theassembly process and also eliminates the raw material costs associatedwith the foam pad and adhesive. Injection molding the interface pad 26also reduces the likelihood of failures between the interface pad andthe base member 4 (i.e. injection molding provides a chemical and/ormechanical bond between the interface pad 26 and base member 4 that isunlikely to allow the interface pad 26 to inadvertently separate fromthe base member 4). The injection molded interface pad 26 may alsoinclude a variety of textures and/or patterns, it may be formed of anynumber of suitable moldable polymer materials depending on the desireddurability and conformability properties, and it may be formed in avariety of colors or thicknesses, thereby greatly increasing the designoptions and design flexibility of the tool, and further allowing thetool design to be easily tailored for specific end uses.

The sanding tool 2 also includes a handle 46. In the illustratedembodiment, the handle 46 includes a neck portion 46 a that extendsupwardly from a central region of the base member 4, and includes anenlarged head portion 46 b located at the end of the neck 46 a thatdefines a knob 48 that can be readily grasped by a user to maneuver andcontrol the movement of the tool 2. To provide the user with a morecomfortable grip, the knob 48 portion of the handle 46 preferablycomprises an interior region 48 a formed of a relatively hard firstmaterial and a peripheral region 48 b formed of a relatively softrubber-like second material that is easier to grip and thereby providesthe user with improved handling. The first relatively hard material, maybe, for example, a hard synthetic plastic, and the relatively softsecond material may be, for example, a thermoplastic elastomer, rubber,rubber-like materials or foam.

The tool 2, including the base member 4, clamping mechanisms 6, 8 andhandle 46, may be formed of any suitable material including, forexample, wood, metal, synthetic plastic, or a stiff rubber.

Those of ordinary skill in the art may appreciate that various changesand modifications may be made to the invention described above withoutdeviating from the inventive concept. For example, it will be recognizedthat the size of the tool may be adapted so it can be used with thevarious standard sizes of commercially available abrasive sheets. Thus,the scope of the present invention should not be limited to thestructures described in this application, but only by the structuresdescribed by the language of the claims and the equivalents of thosestructures.

1. A hand-held, manually-operated, sanding tool for use with areplaceable sheet-like abrasive material, comprising: (a) a base member;(b) a molded interface pad provided on the base member to define aworking face against which the sheet-like abrasive material is arranged;and (c) a retaining mechanism arranged to maintain the sheet-likeabrasive material in operative relation with the interface pad; whereinthe base member is formed of a first material and the molded interfacepad is formed of a second, injection moldable, material.
 2. A sandingtool as defined in claim 1, wherein the first material has a Shorehardness that is greater than the Shore hardness of the second material.3. A sanding tool as defined in claim 2, wherein the second material hasa Shore A hardness of less than about
 95. 4. A sanding tool as definedin claim 3, wherein the first material has a Shore D hardness of greaterthan about
 30. 5. A sanding tool as defined in claim 1, wherein theinterface pad is a polymeric material.
 6. A sanding tool as defined inclaim 5, wherein the interface pad is an elastomeric material.
 7. Asanding tool as defined in claim 6, wherein the interface pad is formedfrom at least one of a thermoplastic elastomer, a thermoplasticvulcanizate, and a thermoplastic rubber.
 8. A sanding tool as defined inclaim 1, wherein the base member is formed of an injection moldablesynthetic plastic material and the interface pad is formed of aninjection moldable material that is softer than the material used toform the base member.
 9. A sanding tool as defined in claim 1, whereinthe interface pad includes a textured surface.
 10. A sanding tool asdefined in claim 1, wherein the interface pad working face includes amacroscopically three-dimensional surface topography.
 11. A sanding toolas defined in claim 6, wherein the surface topography comprises aregular non-random pattern defined by raised regions and recessedregions.
 12. A sanding tool as defined in claim 1, wherein the basemember contains slots, and the interface pad includes extensionsextending into the slots, thereby to form a secure connection betweenthe base member and the interface pad.
 13. A method of making thesanding tool of claim 1, comprising the steps of: (a) providing asanding tool including a base member having a working face; and (b)forming the interface pad on the base member by injection molding anelastomeric material over the working face.
 14. A sanding tool asdefined in claim 1, wherein the retaining mechanism is configured toreleasably retain the sheet-like abrasive material.
 15. A sanding toolas defined in claim 1, wherein the retaining mechanism comprises atleast one clamping mechanism arranged to secure the sheet-like abrasivematerial to the sanding tool.
 16. A sanding tool as defined in claim 1,wherein the retaining mechanism comprises two clamping mechanismspivotally connected on opposite ends of the base member to secure thesheet-like abrasive material to the sanding tool.
 17. A sanding tool asdefined in claim 1, wherein the interface pad is molded to the basemember.
 18. A sanding tool as defined in claim 1, wherein the sandingtool is user-powered without a motor.
 19. A sanding tool as defined inclaim 1, characterized by an absence of adhesive between the base memberand the interface pad.
 20. A sanding tool as defined in claim 1, whereinthe interface pad is directly affixed to the base member.